Radiation protective enclosure having a door which pivots into the enclosure



J. G. SCHNEEMAN 3,488,495 RADIATION PROTECTIVE ENCLOSURE HAVING A DOOR WHICH PIVOTIS INTO THE ENCLOSURE Filed Oct. 20, 1965 2 Sheets-Sheet 1 Jan. 6, 1970 Filed Oct. 20, 1965 J. G. SCHNEEMAN 3,488,495 RADIATION PROTECTIVE ENCLOSURE HAVING A DOOR WHICH PIVOTS INTO THE ENCLOSURE Y 2 Sheets-Sheet 2 1 5 j 02 a? g 76 f n n 11 fj $.74 63 5 INVENTQR. Juan/v 6. 5Z'H'A/EEM4A/ #rraemaas United States Patent ()fiice 3,488,495 Patented Jan. 6, 1970 3,488,495 RADIATION PROTECTIVE ENCLOSURE HAVING A DOOR WHICH PIVOTS INTO THE ENCLOSURE Justin G. Schneeman, 11001 Wrightwood Lane, Studio City, Calif. 91604 Filed Oct. 20, 1965, Ser. No. 498,770 Int. Cl. G01m 21/00, 23/20; H01j 37/20 US. 'Cl. 250-52 8 Claims ABSTRACT OF THE DISCLOSURE Radiation protective enclosure constructed of a radiation absorbing material which generally surrounds a surface on which a specimen can be supported except for an opening in one portion thereof. A pivotal door also constructed of radiation absorbing material passes through the opening to close the same during the radiography process. The door mates with a depression in the support surface in the closed position to prevent the escape of radiation. The door shields the support surface from radiation from the source when the door is moved to the open position.

The present invention relates to radiography and, more specifically, to a protective enclosure in which specimens can be radiographically examined in quick succession on either a production line basis or an individual basis.

. An important object of my invention is to provide a radiation protective enclosure which can be opened to expose a very large area of access for placing the item or specimen to be examined. When the device is opened, there are no walls confining the target area in which the specimen is to be set up on at least three sides, whereby specimens nearly as large as the enclosure can be handled. This arrangement also has special advantages for use with a conveyor belt mechanism serving one or a plurality of individual enclosures.

It is also an object of the invention to provide a protective enclosure in combination with a conveyor belt having sealing means to effectively prevent the escape of radiation from the enclosure, despite the presence of the conveyor belt and to achieve this in a manner which does not interfere with the handling of specimens in quick succession.

A further object of the invention is to provide an enclosure of this type with a door which additionally serves the dual functions of blocking a radiation window immediately upon any opening movement and also serves to swing a reflector into and out of operative relationship to a light source to project a shadow image useful in setting up a specimen for inspection.

The foregoing and other objects and advantages of my I invention will be apparent from the following description of a presently preferred embodiment thereof, when taken in conjunction with the drawings.

FIGURE 1 is a perspective view of a protective enclosure in combination with a conveyor belt mechanism, incorporating my invention.

FIGURE 2 is a vertical sectional view taken on the line 2-2 of FIGURE 1.

FIGURE 3 is a partial sectional view, on a larger scale, taken on the line 3-3 of FIGURE 2.

FIGURE 4 is a view like FIGURE 2, but showing the door in open position to both block the radiation window and to dispose a reflector in operative association with a light source.

FIGURE 5 is a horizontal sectional view taken on the line 5-5 of FIGURE 4.

The drawings show a protective enclosure which may be characterized as of medium size and in combination with a conveyor belt mechanism. However, this representation is to be understood to be illustrative only as the invention is not limited with respect to the size of the enclosure and the enclosure itself has utility apart from use with a conveyor belt.

The enclosure, designated generally by the numeral 10, has a base portion 11 surmounted by a housing 12. A work table 13 is cantilevered forwardly from the rear of the enclosure 10 and projects out of housing 12 in vertically spaced relation to the base portion. 11. Thus, there is provided a clearance between the base 11 and table 13 for the reception of the framework of a conveyor mechanism, designated generally by the numeral 14, that can be wheeled into and out of operative relationship to the work table 13. This mechanism is provided with an endless conveyor belt 15 whose upper flight passes over the top of the work table 13. A visor type of door 16 is pivotally mounted in the housing 12 and when raised, permits access to the table 13 both through the opposite sides as well as from the front. When the door is raised, it frees the belt 15 for movement and when closed on the arrested belt, it provides a radiation seal against the work table 13, despite the presence of the belt.

More specifically, the enclosure includes a rear wall 20, an abbreviated front wall 21 and opposite side walls 22 and 23, all of which are lead lined. The upper end of the cabinet is closed by a lead lined roof 24, which may be below the upper edges of the walls of the cabinet to provide a compartment within which a source of radiation 25 is recessed in the forward portion of the compartment. Alternatively, especially in large devices, the source 25 could be mounted under the roof and movable, rather than fixed in place. The work table 13 is also provided with a lead lined floor 26 (although, alternatively, fluoroscopic or other viewing apparatus could be integrated into the work table) and, as illustrated by the drawings, all of these various surfaces or wall members, are supported on a rigid framework, which may be made up of appropriate angle iron members. As the composition and assembly of the various structural members and wall members is conventional, they will not be described in detail.

The door 16 resembles a segment of a cylinder and is comprised of a lead lined front wall 30 of generally arcuate configuration and opposite side walls 31 of approximately triangular shape. In order to support the door 16 for pivotal movement on a horizontal axis, a pair of saddles 32 are secured to the floor members 16 on opposite sides of the cabinet and mount a pair of pillow blocks 33 receiving the opposite ends of a pivot shaft 34 that supports the door 16.

As is apparent, the lead lined door 16 may be very heavy where strong radiation sources are used, and, accordingly, a power means is provided for effecting raising and lowering of the door (although power need not be used with small bench type enclosures). Further, as the accidental falling of the door could be very hazardous to the operator, a counter-balancing means is provided, preferably so arranged that the door has a rising tendency after a predetermined amount of opening movement, say 5. The counterbalancing, in turn, allows the use of a relatively low level power source just suflicient to provide starting inertia and preferably of sufficiently low level that it can be successfully resisted manually, should the operators hands or arms inadvertently be caught in the path of the lowering or raising hood. In very large installations, where larger power requirements are necessary, a slip clutch can be provided in the driving mechanism for disengagement of the power upon encountering a predetermined level of resistance.

In the preferred embodiment of the invention, the power means for raising and lowering the door includes a motor 36 mounted on a shelf 37 affixed to the rear wall of the cabinet. The output shaft of the motor 36 may extend into a reduction gear box (not shown), if desired, and drives a sprocket 38. A pair of spaced shafts 39 and 40 are mounted on the side wall 22 of the housing at rear and forward locations, respectively. A chain 41 drivingly interconnects the small sprocket 38 to a larger sprocket 42 on the shaft 39 and another smaller sprocket 43 on the shaft 39 is drivingly interconnected to a sprocket 44 on the shaft 40 by a chain 45. Thus, a further drive speed reduction may be effected and it will be understood that the motor 36 is selectively reversible by an external switch means, not shown, whereby to drive the chain 45 in either direction.

The upper end of the door 16 is framed by channelshaped members 48 aflixed to the outer sides of the side walls 31 and another channel 49 aflixed to the outer side of the front wall 30. As is shown in FIGURE 4, these framing members provide a means for rigidly securing a spaced pair of brackets 50 at one side wall 31 of the door 16, adjacent the Wall 22 on which the drive chain 45 is mounted. These brackets 50 support opposite ends of a rod 51 that, in turn, slidably supports a collar 52 that, in turn, has a pivotal connection 53 to the drive chain 45. As the collar 52 is slidable on the rod 51, the drive chain 45 will not be deflected out of a linear run between the sprockets 43 and 40 and breakage of the chain is thus avoided. The frame members 48 of the door also provide means for connection of the counter weight. Thus, a pair of channel-shaped arms 55 are rigidly secured to the inner ends of opposite ones of the channels 48 and at their outer ends support opposite ends of a counter weight 56.

The opening for the door 16 in the cabinet 12 is also framed with channel-shaped members adapted to coact with the members 48 and 49 on the door to provide a radiation seal around the upper edge of the door when it is closed. Thus, a channel 58 is secured horizontally along the upper edge of the door opening on the inside of the cabinet while channels 59 are secured on the inside of the cabinet along the side edges of the door opening. As the channel members 58 and 59 framing the door opening face upwardly and the channel members 48 and 49 on the door face downwardly, when the door is closed the opposing channels 49 and 58 and opposing channels 48 and 59 will nest together as illustrated in FIGURE 2. As a result there is no discontinuity in the protective lead lining of the device when the door is closed and the nesting feature is an efiicient battle against the escape of radiation.

Referring to FIGURE 2, the roof 24 is formed with a window 60 directly beneath the radiation source and the source is positioned to direct a beam 61 along an axis 62 that is normal to the plane of the work table 13. Accordingly, a lead pad or block 63 is aflixed to the upper surface of the lead lined floor 26 to cover at least the area within the direct beam 61 and means are provided in this pad and along the lower edges of the door 16 to effect a radiation-tight seal when the door is lowered. For this purpose, referring to FIGURE 5, the upper surface of the pad 63 is formed with a U-shaped groove 64 and 65 that bounds the opposite sides and the front edge of the pad. The side grooves 65 are interrupted by overlapping grooves 66 that are relatively wide and relatively shallow as compared to the width and depth of the grooves 65. The length of the intermediate grooves 66 exceeds the width of the conveyor belt 15, which passes between the interrupted ends of the grooves 65.

As is shown in FIGURE 3, the grooves 66 are formed with a shallow curvature into which the belt 15 can be depressed without any sharp bending. For mating engagement with the pad grooves 64, and 66, the lower edge of the door is framed with angle iron members 68 positioned above the lower edges of the door walls 30 and 31, sufficiently so that when the angle iron members 68 are at rest on the pad 63, edge portions of the door are received within the slots 64 and 65. As is best seen in FIG- URE 4, depending edge portions of the side walls 31 of door 16 are cut away and a pair of brass or lead straps 69 are secured to the lower flanges of the pair of angle iron members 68 on the door, having a configuration to nest in the shallow grooves 66 of the pad. Thus, when the door is lowered to closed position, the straps 69 depress portions of the belt 15 into the shallow grooves 66. To accommodate this depression of the belt 15, the belt is preferably made of a thin plastic material, on the order of 10 mils in thickness, and is preferably of a slightly elastic nature. The material known as Mylar is suitable for this purpose. Obviously, the belt material should be selected to accommodate the weight and size of the objects to be examined.

While not shown, it will be understood that the apparatus is provided with conventional means or controlling the radiation source 25 and also, with conventional safety devices. For example, whether or not the hood assembly is power operated, there will be switches arranged to prevent energizing of the source 25 as soon as the hood rises and the hood must be completely closed before the source can be energized. The device may also be provided with a warning light exteriorly located on the front of the cabinet, or other annunciator, that is energized during the radiation cycle.

In the event the radiation source 25 is left energized, because of a safety switch failure or due to inadvertance, the relationship of the hood 16 to the radiation window 60 is such that the hood immediately blocks the Window upon starting its upward travel from a closed position. This is .clear from an inspection of FIGURE 2, wherein it will be seen that the upper edge of the closed hood 16 borders the radiation beam 61. Thus, immediately upon the hood being raised, it intercepts the beam 61 and, being lead lined, prevents penetration of the beam. As is apparent from FIGURE 4, this blocking effect of the door 16 is effective in the fully raised position of the door 16 and throughout the movement of the door between fully raised and fully lowered positions.

To aid in setting up the specimen and locating it properly in the target area of the beam, means are provided in the cabinet to project a light beam along the axis 62. This light beam accurately simulates the direction and area of the radiation beam and is used to produce shadow images of the item to be examined, duplicating the area that will be covered by the radiation exposure. For this purpose, a U-shaped bracket 72 is secured to the rear Wall 20 of the enclosure to project forwardly and adjustably support a lamp housing 73. A mirror 74 is aflixed to the inside of the front wall 30 of the door 16, adjacent the lower edge of the door. As is shown, in FIGURE 4, when the door 16 is fully raised, the mirror 74 is positioned opposite an opening 75 in the lamp housing so that a light beam 76, from an incandescent bulb 77 within the housing, is projected onto the mirror. Stop means to fix the fully raised position of the door, wherein the light and mirror are in the desired relationship, may comprise abutting portions of the door 16 and housing 12, for example. The mirror is placed at such distance from the bulb 77 and disposed at such angle that the reflected light beam is coincident with the beam 61. Therefore, a specimen 78 resting on the work table will project a shadow coinciding with the image that will be projected by the radiation beam 61 When the source 25 is energized. As will be evident, the specimen 78 can be adjusted and set up to produce the desired shadow image corresponding to the desired radiation image. This-feature is primarily useful when the enclosure is used independently of the conveyor mechanism 14, but may also be used with the conveyor mechanism, for purposes of starting and stopping the conveyor belt 15 at the right moment to properly locate the specimen 78 with respect to the target area. i

The conveyor belt mechanism 14 is also made of conventional material in a conventional manner and accordingly, the details of construction will not be described in detail. The mechanism is, however, of novel configuration in being especially adapted for use with the enclosure and, also, in'the nature of the belt and its coaction with the door 16 and table 13 to produce a radiation seal. In any event, the mechanism 14 has left and right opposite end portions 80* and 81, respectively, that are spaced apart to freely but closely receive opposite sides of the table 13 therebetween. The portions 80 and 81 are rigidly interconnected by a framework 82 mounted on four legs 83 that are provided with castered Wheels 84 on their lower ends. While not visible, it will be understood that the opposite end portions 80 and 81 are provided with rollers and bearing surfaces supporting the belt 15 at such height that the upper flight of the belt will pass over the lead pad 63 so that specimens can be carried into and out of the enclosure 10 when the door 16 is raised.

With this arrangement, the conveyor mechanism 14 can be wheeled into and out of operative position with respect to the work table 13. While not shown, it will be understood that the mechanism is provided with a conventional power means for gradually stopping and starting the belt 15. When the conveyor mechanism 14 is in position, a specimen 78 can be setupalong the mid-line of the belt 15 on the left end portion 80 of the conveyor mechanism, being placed on top of asheet of film 85. Then, assuming the door 16 to be opened, the conveyor belt 15 is turned on to carry the specimen 78 into position on the work table 13. When the specimen 78 is properly located within the target area, as indicated by the shadow image cast by the light bulb and mirror arrangement, the belt 15 is stopped; Then the door 16 is lowered and the source can then be energized. A new specimen can then be set up on a piece of film on the left hand portion 80 and after the setup is completed, the radiation cycle of the source 25 will have been completed, so that the door 16 can be raised. Then, the belt 15 is again turned on to carry the specimen 78 off of the work table 13 and onto the right hand portion 81 of the conveyor mechanism 14, simultaneously moving a new specimen into position on the work table. Door 16- is again lowered into position and the source 25 turned on, and during the ensuing radiation cycle, the exposed film 85 and specimen 78 may be removed from the right hand portion 81 and a new set up made on the left hand portion 80.

Although but a single embodiment of the invention is herein shown and described, several variations thereof will occur to those skilled in the art. Accordingly, it is to be understood that I do not wishto be limited to the exact details of construction set forth above, but only by the spirit and scope of the following claims.

I claim:

1. A radiation-protective enclosure for use in radiography comprising:

a surface on which a specimen can be positioned to be subjected to radiation directed at the surface;

a. housing rigidly interconnected to and partially enclosing said surface and having edge portions defin ing an opening of said housing in a plane intersecting the plane of said surface at an acute angle so that at least a portion of the area of said surface is disposed laterally outside of said housing and in confronting alignment with said opening;

a door pivotally connected to said housing on a pivot axis that is substantially parallel to the intersection of said planes and adapted and arranged for passage of said door inwardly and outwardly through said opening and into and out of contact of one edge of said door with said surface;

said door having shape characteristics, including angularly related side and end wall portions of said door, such that when said one edge of said door-is in engagement with said surface, portions of said door surround all portions of said surface not enclosed by said housing; and

lining means for said surface, said housing and said door adapted to prevent escape of radiation from said enclosure when said door is in engagement with said surface. r

2. A device as in claim 1 in which a counterbalancing means is connected to said door and includes means to normally bias said door to an open position.

3. A device as in claim 2 in which said surface is horizontally disposed and said door is mounted for swinging on a horizontal axis, said means to bias said door to open position being adapted to be ineffective when said door engages said surface.

4. A device as in claim 1 in which a reflector means is mounted on the inside of said door for co-movement with said door and said housing is provided with a means for positioning a light source therein to project light onto said reflector means when said door has been moved to an open position, said reflector means being adapted to reflect light onto said surface when said door is in said open position to produce on said surface a shadow image of a specimen on said surface.

5. A device as in claim 1 in which said means to prevent escape of radiation include portions of said surface and door that are matingly engageable when said door contacts said surface.

6. A device as in claim 5 in which a conveyor means is provided for carrying a specimen into and out of position on said surface,

said conveyor means including a flexible belt arranged for movement over said surface and across said matingly engageable portions of said door and sur face,

said matingly engageable portions including shallow areas into which portions of said belt can be depressed to at least a depth exceeding the thickness of the material of which said flexible belt is made.

7. A radiation protective device for examining specimens in succession comprising:

a horizontally disposed work table;

a conveyor belt means including a flexible belt means extending across said table from one side to the other and extending beyond opposite sides of said table;

a housing rigidly interconnected to said table and formed with a downwardly facing opening, said table and housing being arranged so that a portion of said table over which said belt means crosses is disposed outside of said housing and in alignment with said opening;

a door mounted on said housing for movement through said opening between open and closed positions of said door, said door in closed position engaging said table and belt means and having shape characteristics such that said door, in closed position, surrounds all portions of said table not enclosed by said housing,

said door and table having cooperating matingly engageable portions into which portions of said belt means can be deflected sufliciently, upon closing of said door, to prevent radiation losses through the area occupied by said belt means.

8. In a radation protective enclosure, the combination comprising:

a housing formed with a downwardly facing Opening;

a work table rigidly secured to said housing to extend horizontally forwardly therefrom in alignment with said opening and to be at least partially disposed outside of said housing,

said work table being of cantilever construction to permit movement of an endless belt of a conveyor means into and out of a position for circum-navigating said table in carrying specimens on and off said table;

a door mounted on said housing for movement through said opening between open and closed positions of said door, said door in closed position engaging said table and having shape characteristics such that said door, in closed position, surrounds all portions of said table not enclosed by said housing,

said door and table having cooperating matingly engageable portions into which portions of a belt means can be deflected upon closing of said door suificiently to prevent radiation losses through the area occupied by said belt means in said matingly engageable por- References Cited UNITED STATES PATENTS tions.

Adrian 250-53 Swaisgood 250-53 Daly 250-52 Moran et a1. 250-65 Peyser 250108 X US. Cl. X.R. 

